Airplane arresting device



Feb. 12, 1963 P. B. FONDEN ETAL AIRPLANE ARRESTING DEVICE Filed April 6. 1960 Bal Federated Feb.

3,677,323 ALRE'LANE ARRES'HNG BEVKIE Ier lliirie Fenders, Gotgatan .23, and Karl Ove Torguy Wiilander, Vasavagen 4?, both of lsinlroping, Sweden Filed Apr. 6, 1969, er. No. 20, 28? 4 Claims. (t'jl. 244-410) The present invention relates to a runaway-preventing implement or arresting device for airplanes and other crafts of the type which consists of a net of two substantially horizontal wires relatively spaced vertically and interconnected by a plurality of substantially vertically extending ropes, so-called plumb ropes.

Since various airplanes dilfer very much in external shape, difiiculty has been experienced in satisfactorily catching various types of airplanes by means of conventional nets having a single kind of plumb ropes. In addition, the nets usually have a good catching effect when an airplane hits the middle portion of the net, whereas .difiiculties arise when the plane hits the net laterally of the middle portion thereof.

The object of the invention is to secure a safe catching of various types of airplanes as well as of airplanes which in emergency situations are unable to fly into the middle of the net.

The invention is characterized by the fact that in addition to said plumb ropes which determine the vertical distance between the horizontal wires there are provided longer plumb ropes disposed, as the shorter one, along the net and extending between the horizontal wires so as, where, on catching an airplane in the net, some of the shorter plumb ropes break, to cause the longer ones to contribute to arresting the airplane.

in the accompanying drawing the invention is illus trated by a diagrammatic elevation of a portion of an embodiment of the invention. It is to be noted that the embodiment shown in only to be considered as an example and not in any way as a restriction of the inyention.

In the example shown reference numerals 1 and 2 designate the upper and lower wires, respectively, of an arresting net otherwise shown.

Said wires are interconnected by substantially vertical ropes, so called plumb ropes, some of which, designated by 3 in the drawing, are such a length as to determine the vertical distance between the wires 1 and 2, whereas the remaining ones, designated by 4, are of greater length.

in the drawing FIGURE 1 is a diagrammatic view of one embodiment of a net according to this invention.

FIGURE 2 is a view similar to FIG. 1 of a modified embodiment of the invention.

in H6. 1 of the drawing, the longer ropes 4- alternate with the shorter ropes 3, this, however, is only shown by way of example in order to illustrate the principle of the invention, as already stated thereinbefore.

The operation is as follows:

The net is adapted to arrest a jet propulsion airplane having air intakes disposed in advanced positions in the fuselage sides, a fuselage-wing portion extending almost parallel to the fore-and-aft avis, and projecting external wings disposed in very retracted positions and forming the actual hold for the net. As such an airplane impinges the net, a few plumb ropes will take hold between the fuselage and air intakes. In the case of a conventional net the plumb ropes of which are all the same length, the projecting wings will not at all contact the net or-if the plumb ropes embracing the air intakes should break-will contact the same too late. By this time, however, the proportion of the total restraining power of the net represented by the first-mentioned plumb 2 ropes will have disappeared which might result in the airplane breaking through the net. in any case the net will have to be dimensioned less favourable than would otherwise be the case.

In case of a net according to the present invention, when impinged by an airplane like that above mentioned, a couple of the shorter plum-b ropes, as 4, will initially place themselves between the fuselage and air intakes. This will stretch the net rearwardly, whereby the longer plumb ropes, as 3, embracing the airplane between the fuselage and air intakes, or embracing the air intakes, as well as the remaining ones of the shorter plumb ropes which embrace the projecting wings, will be rather uniformly stretched simultaneously, thus allowing both the long and the short plumb ropes to contribute to the arresting and deceleration of the airplane.

Where a heavy passenger trafic plane is concerned, it may be of advantage to use a net having no plumb ropes at all in its middle portion, as indicated in FIG. 2, where normally the airplane can be expected to hit the net, the purpose of this arrangement being to protect the cabin where the passengers are housed, or to prevent doors of the cabin from getting obstructed, thus rendering it difficult for the passengers to leave the plane. Taking these factors into consideration, the plumb-ropes lengths are chosen to give a favourable distribution of forces over the airplane. It should be. observed that the force distribution is much more critical as regards large airplanes than it is in respect of smaller ones which is due to the fact that the relative strength of large airplanes is much less than that of small ones.

ere is nothing to guarantee, however, that a tramc plane in an emergency situation will hit the middle portion of the net, but the plane could fly into the net laterally thereof. In such case, in a conventional net, the calculated distribution of plumb-rope lengths will not be the proper one, which could result in the breaking of certain plumb-ropes. However, if the net is provided with secondary plumb ropes of greater lengths than the primary ones, in conformity with the invention, then the lengths of the secondary plumb ropes will adapt themselves in such a way that those embracing the wing next to the middle of the net, together with the primary plumb ropes embracing the other wing will establish a favourable distribution or" the forces over both wings of the airplane.

We claim:

1. A runaway-preventing net for airplanes placeable in a substantially vertical plane across a runway which comprises in combination, an upper and a lower supporting wire extending in substantially horizontal directions along the entire length of the net, a set of ropes each connecting substantially vertically aligned points of the upper and lower wires and of a length determining the vertical distance between said wires, and another set of ropes each connecting substantially aligned points of the upper and lower wires but of a greater length than said distance therebetween, so that in the normal state of the not each of them forms a loop depending below the lower wire.

2. A runaway-preventing implement for airplanes as claimed in claim 1, and in which each two vertically aligned points of the wires are connected together both by a rope determining the distance between said points and a rope of greater length.

3. A runaway-preventing implement as claimed in claim I, and in which there is a middle portion of the net free from ropes, and in which there is a rope of the greater length provided on each side of said portion.

4. A runaway-preventing implement as claimed in claim 1, characterized in that said shorter and longer ropes are provided alternately viewed in the longitudinal direction of the net.

References Cited in the file of this patent 4 Sawyer Nov. 25, 1941 Cotton Sept. 30, 1958 FOREIGN PATENTS Great Britain June 28, 1946 Great Britain Feb. 7, 1949 

1. A RUNAWAY-PREVENTING NET FOR AIRPLANES PLACEABLE IN A SUBSTANTIALLY VERTICAL PLANE ACROSS A RUNWAY WHICH COMPRISES IN COMBINATION, AN UPPER AND A LOWER SUPPORTING WIRE EXTENDING IN SUBSTANTIALLY HORIZONTAL DIRECTIONS ALONG THE ENTIRE LENGTH OF THE NET, A SET OF ROPES EACH CONNECTING SUBSTANTIALLY VERTICALLY ALIGNED POINTS OF THE UPPER AND LOWER WIRES AND OF A LENGTH DETERMINING THE VERTICAL DISTANCE BETWEEN SAID WIRES, AND ANOTHER SET OF ROPES EACH CONNECTING SUBSTANTIALLY ALIGNED POINTS OF THE UPPER AND LOWER WIRES BUT OF A GREATER LENGTH THAN SAID DISTANCE THEREBETWEEN, SO THAT IN THE NORMAL STATE OF THE NET EACH OF THEM FORMS A LOOP DEPENDING BELOW THE LOWER WIRE. 